Here is a reason Dougie wants to know his mpg precisely.Keeping this strictly to US and state highways and not ‘the baaaaad part of town at night’ ,where do you NOT want to run out of gas. There is a highway from Alpine,Texas north a hundred miles or more to interstate 10. It is straight as an arrow over flat as a griddle land. You can see for miles in all directions. There are mountains awayyyyyyy off on the horizons.At least the peaks the bases are below the horizon. There is nothing but desert, no ranch,no house, no sign of humanity. I drove it once(for ever) and did not meet or see one car behind or front the whole trip. Finally we came to a small rise,“What the heck is that way up ahead?” I most had a heart attack when a car appeared just as we both reached the crest.It was a Highway patolman,and he was just turning around to get back on the interstate at the bottom of the rise. “Look at ALL the cars!!” Musta been a dozen of them in plain sight. No gas station or any thing at the intersection. More endless miles north till Guadalupe Natl. Park. The sight of all that peoplelessness was great, but I was glad I had a new can of Coleman fuel.If we ran out of gas I could take that can of gas and cook something to eat for the next few days till some one showed up.